/Engine/Plugins/Media/ElectraCDM/Source/ElectraCDM/Public/ElectraCDM.h
Obtains the CDM system's preference on how attributes and text properties should be prefixed in the JSON string passed to GetCDMCapabilitiesForScheme(..., InAdditionalElements) or in theFCDMCandidate.AdditionalElements.
void GetCDMCustomJSONPrefixes ( const [FString](API\Runtime\Core\Containers\FString) & InCDMScheme, const [FString](API\Runtime\Core\Containers\FString) & InValue, [FString](API\Runtime\Core\Containers\FString) & OutAttributePrefix, [FString](API\Runtime\Core\Containers\FString) & OutTextPropertyName, bool & bOutNoNamespaces )